Fibers, yarns and filaments of waterinsoluble dextran



United s] Pasfl ifl FIBERS, YARNS AND FILAMENTS OF WATER- INSOLUBLE DEXTRAN Malvern J. Hiler, Dayton, Ohio, assignor to The Coinmonwealth Engineering Company of Ohio, Dayton, Ohio, a corporation of Ohio No Drawing. Filed Aug. 30, 1955, Ser. No. 531,587

Claims. (Cl. 28-'-82) This invention relates to shaped articles including fibers, yarns and films consisting essentially of waterinsoluble dextran.

The object of the invention is to provide new shaped articles of water-insoluble dextran, particularly fibers and films.

The dextrans are high molecular weight polysaccharides made up of anhydroglucopyranosidic units joined by molecular structural repeating 1,6 and non-1,6 linkages, at least 50% and usually a preponderant proportion of the linkages being of the 1,6 type.

The dextrans may be obtained by the action of specific microorganisms such as those of the Leuconostoc mesenterozdes or L. dextranicum types on sucrose. The procedure is to inoculate a suitable aqueous sucrosebearing nutrient medium with a culture of the microorganism or with the enzyme filtered from the culture, and incubate the mass until the dextranis produced in maximum yield, when it is separated, from'theferm'entate and purified. The native dextran' thus obtained normally has a high molecular weight calculated to be in the millions.

This invention contemplates the formation of fibers and films especially from dextrans which are inherently insoluble in water but soluble in aqueous alkali or from xanthates of those dextrans from which the dextran'is regenerated during shaping thereof.

Microorganisms (or their enzymes) which may be used to effect biosynthesis of the water-insoluble, alkalisoluble dextran include those bearing the following NRRL (Northern Regional Research Laboratory) designations: Leuconoszoc mesenteroides B-523, B1l18, B1120, B-

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drawn from the bath, preferably stretched between godets or other suitable take-up devices or stretching means, and dried. During the stretching, the fibers or film may be subjected to a spray of warm or even hot Water which 5 maintains the article in plastic condition whereby the 1139 and Bll44. The dextran may be the native unhydrolyzed dextran or it may be hydrolyzed to a dextran of lower molecular weight between that of the native product and that at which the hydrolyzate remains insoluble in water. The molecular weight may be as low as 50,000 depending on the ratio of 1,6 to non-1,6linkages of the dextran. I v.

The spinning or casting dope is obtained by dissolving the dextran or xanthate thereof in aqueous alkali, such as and preferably a 4% to 10%-aqueous sodium hydroxide solution, and spinning or casting the dope through a spinneret or film-forming device into a bath in which the dextran is coagulated in the fiber or film form. Solutions of, for example, 10 to of the dextran or dextran xanthate in aqueous sodium hydroxide may be used.

When the dope is an aqueous alkaline solution of water-insoluble dextran, the'setting bath may be water. Dilution of the aqueous alkali extruded with the dope by the water efiects coagulation of the water-insolubledextran in the filament or film form. The bath is circulated Fibers and films formed in the water bath with.

stretching and orientation for improvement in tenacity is facilitated.

Conventional apparatus is used.

Dextran xanthate for. use in preparing the spinning dope may be obtained by mixing liquid or gaseous carbon disulfide with an aqueous slurry of the alkali derivative or the dextran (obtained by reacting the dextran with a strong alkali metal hydroxide and notably with sodium hydroxide) and maintaining the mix at a temperature of 20 C. to 25 C. until the desired degree of substitution with respect to xanthate groups is obtained, usually 2 to 4 hours using a molar ratio of alkali dextran to carbon disulfide of 1:3 to 12:1. The ester may contain an average of 0.2 to 3.0 xanthate groups per anhydroglucopyranosidic unit of the dextran.

The dextran xanthate spinning or casting dope is prepared by dissolving .the xanthate in aqueous alkaline solution, e.g., 410% aqueous sodium hydroxide, and is spun or cast into an acid coagulating and regenerating bath, such as an aqueous solution of sulfuric acid which may contain sodium sulfate and zinc sulfate, in which bath the de-xanthation is at least initiated, with coagulation of the dextran in the fiber or film form. Baths containing 512% sulfuric acid, 620% sodium sulfate and 05-15% of zinc sulfate may be used.

The fibers or film are withdrawn from the bath, washed free of occluded bat-h constituents, and, preferably before or during drying, stretched between godets or the like. Softening agents, anti-blocking agents and the like may be incorporated in the films, as a'step in their manufac- The following examples are illustrative of specific embodiments of the invention, it being understood that these examples are not limitative.

Example I A 10% solution of purified native (unhydrolyzed) L.m. B523 dextran in particulate condition is dissolved in 6% aqueous sodium hydroxide at room temperature, with stirring.

The homogeneous dope thus obtained is extruded through a spinneret into continuously circulating water maintained at 50 C. The filaments formed by dilution of the aqueous alkaline solution extruded with the dextran are drawn through the bath a distance of 6 inches, withdrawn over a godet to a second godet rotating at higher peripheral speed whereby the fibers are stretched. The extent of stretching may berup to 50% of the initial length and may be facilitated by passing the fibers through a warm water bath (50 C.-60 C.) supported between the godets or by subjecting the fibers between the godets to a spray of the warm water. After drying, the fibers are collected on a spool, bobbin or other appropriate take-up device, with or without prior application of a soft finish. The fibers may be given a finishing coating of a dextran, particularly a dextran of relatively low molecular weight (500050,000) dissolved in water, as a substitute for starch, and dried before or during winding up thereof. These fibers have tensile strengths and elongations comparable to those of regenerated cellulose from cotton linter pulp and are useful for all textile purposes, including blending of ,thestaple fibers r 3 with short fibers of other types for the production of spun yarn and so-called non-Woven fabrics.

Example 11 Example 111 A spinning dope is prepared by dissolving 10% of native L.m. B-523 dextran xanthate containing an average of 2.0 xanthate groups per AGU in 6% aqueous.

sodium hydroxide. The dope is extruded through a spinneret into a coagulating and regenerating bath com-. prising an aqueous solution of 8% sulfuric acid, 11.5% sodium sulfate and 1% zinc sulfate maintained at 50-55" C., and circulated for refreshing as required. The filaments are drawn through the bath a distance of 8 inches, withdrawn, and either as arunning length or after collection in an annular package or cake in a centrifugal spinning bucket are finally washed. with Warm water to remove occluded bath constituents, and dried. The washing and/or drying may be performed while the filaments are under stretching tension.

' Example IV .a film-forming device, the film -is drawn through thebath a distance of 8 inches, withdrawn, washed and dried, and at some stage, or at all stages, between withdrawal from the bath and final drying, is subjected to tension whereby it is stretched 25% of its initial length and 5% of its initial width. i

The film may be provided with a moistureproofing coating. Particularly suitable coatings are lacquers comprising benzyl dextran or nitrodex-tran, the latter being a new substance which may be prepared by the method dm'cribed the pending application of L. J. Novak et al., filed February 11, 1954, Serial No. 409,781,

and now abandoned. p

As described in said pending application, dextran nitrate may be obtained by rcactingon dextran, in solid particulate condition or dispersed in water, with concentrated nitric acid, fuming nitric acid or a mixture of nitric, acid :and nitrogen pentoxide, and precipitating-the nitrate from the reaction mass, for instance, by means of isopropanol. l I

A suitable lacquer coating composition may be -obtained by dissolvinga percent by weight Nitrodextran or benzyl dextran 57.0 Dewaxed damar 13.0 Dibutyl phthalate 23.0 Parafiin wax a n a a aa 4.0 Zinc stearate 1.0

in an appropriate solvent or mixture of solvents, such as a mixture of 55.1% ethyl acetate, 3.5% denatured eth- Example V dextran of molecular weight about 200,000, in 5% aqueous sodium hydroxide.

Example VII Example I is repeated, using a dope which is a solution of native, unhydrolyzed B4118 dextran in 7% aqueous sodium hydroxide.

Example VIII Example III is repeated except that the dope extruded through the spinneret into the acid bath is a solution of native L.m. B-1118 dextran xanthate containing an average of 2.3 xanthate groups per AGU in 6% aqueous sodium hydroxide.

Example IX Example X Example I is repeated, using a 6% aqueous sodium hydroxide solution of native, unhydrolyzed L.m. Bll44 dextran.

Example XI Example H is repeated, using as dope a 4% aqueous sodium hydroxide solution of hydrolyzed 'L.m. B4144 dextran having molecular weight about 500j000.

Example XII Example I is repeated using a dope consisting of a 10% aqueoussodiurn hydroxide solution of native, unh'ydrolize'd L.m. B41 20 dextran.

. In general, the filaments of the water-insoluble dextran may be given a stretch of about 20% to in the course of their production. Films of the dextran may be stretched 20% to 30% of the initial length, 5% to 10% of the initial width. As noted above, conventional means may beempioyed for spinning or casting the dope to obtain 'the filaments or films, and for stretching the same.

The filaments of the invention may be formed into yarns which'may be twisted in the usual way, and the yarns may "be fabricated by conventional textile working methods, or disrupted to obtain a mass of discontinuous fibers for the production of a spun yarn' or non-woven fabric either alone or in admixture with other fibers which latter may be natural, artificial or synthetic 'fibers.

For instance, from 15% to 65% of the dextran fibers may be carded and/or combined with fibers of-cotton,

- rayon, nylon, 'Orlon,. Dacron, Acrilon, -or mixtures Example I is repeated except that the dextran disso1ved in the aqueous alkali is hydrolyzed L.m. B-523 dextran having a molecular weight of about 50,000.

I Example VI Example-II is repeated except that the dope extruded to form {the film is .a solution ofhydrolyzedlm. B-523 'of such fibers and'spun into a yarn. 0r yarns of the dextran fibers may betwisted with yarns formed from the other fibers or mixtures thereof. Y For'the production of non-woven fabrics, blends of the discontinuous dextran'fibe'rs with fibers of'the type mentioned, rayon flock, leather scrap and so on, may be as sembled in the form of a mat or bat and the assembly may be treated with an extraneous binder or adhesive which bonds the:fibers into an'integral coherent structure. A 3% to 10% aqueous solution or inherently adhesive dextran xanthate may be used as the binder, although other binders are also satisfactory. f Informing the bat or web, the fibers of'which the dextran fibers {amount to 15% to by Weight, may be carded :together-to obtain a web in which the fibers are arrayed :in substantially parallelized condition, or they may be suspended in a current of air and deposited'from the suspension on a reticulated collecting surface with or "without the aid of :suction. "The dextran fibers tend to become "adhesive when exposed to aqueous alkali, and this latent adhesiveness maybe developed to permit autogenous bonding of mixedrfibers in a yarn, non-woven fabric or web, etc., care being taken that the action of the aqueous alkali on the fibers is controlled so that the fibers are softened to the adhesive condition while, preferably, retaining the fiber form.

The fibers and yarns and structures formed therefrom are generally useful except under conditions involving exposure thereof for any appreciable time to alkaline conditions. They may be used in constructing tire cords, in conjunction with yarns of other types, and brought to adhesive condition for bonding with rubber.

Since changes and variations may be made in practicing the invention without departing from the spirit and scope thereof, it will be understood that it is not intended to limit the invention except as defined in the appended claims.

What is claimed is:

1. As an article of manufacture an attenuated waterinsoluble, dry filament of dextran of molecular weight of about 200,000 and composed essentially of dextran xanthate.

2. A shaped article consisting of fibers which fibers are composed essentially of water-insoluble dextran Xanthate containing an average of 0.2 to 3.0 xanthate groups per anhydroglucopyranosidic unit of the dextran, and having a molecular Weight between 50,000 and 500,000.

3. Fibers and filaments consisting essentially of waterinsoluble dextran consisting of unhydrolyzed L.m. B523 dextran.

4. Yarns comprising fibers consisting essentially of Water-insoluble dextran xanthate containing an average of 0.2 to 3.0 xanthate groups per anhydroglucopyranosidic unit of the dextran.

5. A Water-insoluble filament consisting of dextran xanthate having a molecular weight between 50,000 and 500,000 and extruded from a solution composed essentially of dextran xauthate dissolved in aqueous sodium hydroxide.

References Cited in the file of this patent UNITED STATES PATENTS 1,559,176 Newkirk Oct. 27, 1925 2,203,705 Stahly et a1. Jan. 11, 1940 2,394,957 White Feb. 12, 1946 2,674,517 Deniston Apr. 6, 1954 2,702,231 Deniston Feb. 15, 1955 2,716,049 Latour Aug. 23, 1955 2,736,652 Novak Feb. 28, 1956 2,775,507 Downing et al Dec. 25, 1956 2,789,915 Bishop Apr. 23, 1957 2,914,414 Novak et al Nov. 24, 1959 

1. AS AN ARTICLE OF MANUFACTURE AN ATTENUATED WATERINSOLUBLE, DRY FILAMENT OF DEXTRAN OF MOLECULAR WEIGHT OF ABOUT 200,000 AND COMPOSED ESSENTIALLY OF DEXTRAN XANTHATE. 